The current generation of Building Automation System (BAS) is designed and operated with little consideration of security of their cyber and physical components. This situation leaves building systems, especially the emerging Grid-interactive Efficient Buildings (GEBs), vulnerable to cyber-attacks that may have adverse or even severe consequences including occupant discomfort, energy wastage, equipment downtime and disruption of grid operation. Current physical behavior based anomaly detection methods fail to differentiate cyber-attacks from equipment or operational faults. Such distinction is needed to ensure appropriate automated control response to cyber threats and provide actionable data to the facility manager. To address these issues, The University of Alabama (UA), in partnership with United Technologies Research Center (UTRC), Drexel University (DU), Arizona State University (ASU), Northwestern University (NU), and Pacific Northwest National Laboratory (PNNL), proposes to research, develop, and demonstrate a CYber Defense and REsilient System (CYDRES), deployable for legacy and emerging BAS, to empower GEB with cyber-attack-immune capabilities. The team members have been collaborating in the area of smart building in the last ten years through ASHRAE, DOE, NSF, and private industry projects.